Patents by Inventor Loc Tu

Loc Tu has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 7606091
    Abstract: High performance non-volatile memory devices have the programming voltages trimmed for individual types of memory pages and word lines. A group of word lines within each erasable block of memory are tested in successive program loops to minimize the problem of incurring excessive number of erase/program cycles. An optimum programming voltage for a given type of memory pages is derived from statistical results of a sample of similar of memory pages.
    Type: Grant
    Filed: September 12, 2006
    Date of Patent: October 20, 2009
    Assignee: SanDisk Corporation
    Inventors: Yan Li, Loc Tu, Charles Moana Hook
  • Patent number: 7599223
    Abstract: In a non-volatile memory, a selected page on a word line is successively programmed by a series of voltage pulses of a staircase waveform with verifications in between the pulses until the page is verified to a designated pattern. The programming voltage at the time the page is programmed verified will be to estimate the initial value of a starting programming voltage for the page. The estimation is further refined by using the estimate from a first pass in a second pass. Also, when the test is over multiple blocks, sampling of word lines based on similar geometrical locations of the blocks can yield a starting programming voltage optimized for faster programming pages.
    Type: Grant
    Filed: September 12, 2006
    Date of Patent: October 6, 2009
    Assignee: SanDisk Corporation
    Inventors: Loc Tu, Charles Moana Hook, Yan Li
  • Patent number: 7561482
    Abstract: A method and apparatus provide an improved identification and isolation of defective blocks in non-volatile memory devices having a plurality of user accessible blocks of non-volatile storage elements where each block also has an associated defective block latch. The method provides for sensing each defective block latch to determine whether the defective block latch was set due to a defect, and storing, in temporary on chip memory, address data corresponding to each set latch. The method further involves retrieving the address data and disabling defective blocks based upon the address data. A non-volatile memory device is also described having a controller which senses the defective block latches, stores address data for each block having a set latch, and subsequently retrieves the stored address data to set the defective block latches based upon the address data.
    Type: Grant
    Filed: September 7, 2006
    Date of Patent: July 14, 2009
    Assignee: Sandisk Corporation
    Inventors: Loc Tu, Wangang Tsai
  • Patent number: 7477545
    Abstract: Memory die are provided with programmable chip enable circuitry to allow particular memory die to be disabled after packaging and/or programmable chip address circuitry to allow particular memory die to be readdressed after being packaged. In a multi-chip memory package, a memory die that fails package-level testing can be disabled and isolated from the memory package by a programmable circuit that overrides the master chip enable signal received from the controller or host device. To provide a continuous address range, one or more of the non-defective memory die can be re-addressed using another programmable circuit that replaces the unique chip address provided by the pad bonding. Memory chips can also be also be readdressed after packaging independently of detecting a failed memory die.
    Type: Grant
    Filed: June 14, 2007
    Date of Patent: January 13, 2009
    Assignee: SanDisk Corporation
    Inventors: Loc Tu, Jian Chen, Alex Mak, Tien-Chien Kuo, Long Pham
  • Publication number: 20080311684
    Abstract: Memory die are provided with programmable chip enable circuitry to allow particular memory die to be disabled after packaging and/or programmable chip address circuitry to allow particular memory die to be readdressed after being packaged. In a multi-chip memory package, a memory die that fails package-level testing can be disabled and isolated from the memory package by a programmable circuit that overrides the master chip enable signal received from the controller or host device. To provide a continuous address range, one or more of the non-defective memory die can be re-addressed using another programmable circuit that replaces the unique chip address provided by the pad bonding. Memory chips can also be also be readdressed after packaging independently of detecting a failed memory die.
    Type: Application
    Filed: June 14, 2007
    Publication date: December 18, 2008
    Inventors: Loc Tu, Jian Chen, Alex Mak, Tien-chien Kuo, Long Pham
  • Publication number: 20080310242
    Abstract: Memory die are provided with programmable chip enable circuitry to allow particular memory die to be disabled after packaging and/or programmable chip address circuitry to allow particular memory die to be readdressed after being packaged. In a multi-chip memory package, a memory die that fails package-level testing can be disabled and isolated from the memory package by a programmable circuit that overrides the master chip enable signal received from the controller or host device. To provide a continuous address range, one or more of the non-defective memory die can be re-addressed using another programmable circuit that replaces the unique chip address provided by the pad bonding. Memory chips can also be also be readdressed after packaging independently of detecting a failed memory die.
    Type: Application
    Filed: June 14, 2007
    Publication date: December 18, 2008
    Inventors: Loc Tu, Jian Chen, Alex Mak, Tien-chien Kuo, Long Pham
  • Patent number: 7457178
    Abstract: A flash memory device of the multi-level cell (MLC) type, in which control gate voltages in read and programming operations and a bandgap reference voltage source are trimmable from external terminals, is disclosed. In a special test mode, control gate voltages can be applied to a selected programmed memory cell so that the threshold voltage of the cell can be sensed. A digital-to-analog converter (DAC) use for programming and a second read/verify DAC apply varying analog voltages and are sequentially used to verify the programming of an associated set of memory cells in this special test mode, with the DAC input values that provide the closest result selected for use in normal operation. These DAC's are dependent on the value of a reference source that my also be trimmed.
    Type: Grant
    Filed: January 12, 2006
    Date of Patent: November 25, 2008
    Assignee: SanDisk Corporation
    Inventors: Loc Tu, Jeffrey Lutze, Jun Wan, Jian Chen
  • Patent number: 7453731
    Abstract: In a non-volatile memory, a selected page on a word line is successively programmed by a series of voltage pulses of a staircase waveform with verifications in between the pulses until the page is verified to a designated pattern. The programming voltage at the time the page is programmed verified will be to estimate the initial value of a starting programming voltage for the page. The estimation is further refined by using the estimate from a first pass in a second pass. Also, when the test is over multiple blocks, sampling of word lines based on similar geometrical locations of the blocks can yield a starting programming voltage optimized for faster programming pages.
    Type: Grant
    Filed: September 12, 2006
    Date of Patent: November 18, 2008
    Assignee: Sandisk Corporation
    Inventors: Loc Tu, Charles Moana Hook, Yan Li
  • Publication number: 20080062785
    Abstract: High performance non-volatile memory devices have the programming voltages trimmed for individual types of memory pages and word lines. A group of word lines within each erasable block of memory are tested successive program loops to minimize the problem of incurring excessive number of erase/program cycles. An optimum programming voltage for a given type of memory pages is derived from statistical results of a sample of similar of memory pages.
    Type: Application
    Filed: September 12, 2006
    Publication date: March 13, 2008
    Inventors: Yan Li, Loc Tu, Charles Moana Hook
  • Publication number: 20080062768
    Abstract: High performance non-volatile memory devices have the programming voltages trimmed for individual types of memory pages and word lines. A group of word lines within each erasable block of memory are tested in successive program loops to minimize the problem of incurring excessive number of erase/program cycles. An optimum programming voltage for a given type of memory pages is derived from statistical results of a sample of similar of memory pages.
    Type: Application
    Filed: September 12, 2006
    Publication date: March 13, 2008
    Inventors: Yan Li, Loc Tu, Charles Moana Hook
  • Publication number: 20080062761
    Abstract: A method and apparatus provide an improved identification and isolation of defective blocks in non-volatile memory devices having a plurality of user accessible blocks of non-volatile storage elements where each block also has an associated defective block latch. The method provides for sensing each defective block latch to determine whether the defective block latch was set due to a defect, and storing, in temporary on chip memory, address data corresponding to each set latch. The method further involves retrieving the address data and disabling defective blocks based upon the address data. A non-volatile memory device is also described having a controller which senses the defective block latches, stores address data for each block having a set latch, and subsequently retrieves the stored address data to set the defective block latches based upon the address data.
    Type: Application
    Filed: September 7, 2006
    Publication date: March 13, 2008
    Applicant: SanDisk Corporation
    Inventors: Loc Tu, Wangang Tsai
  • Publication number: 20080062765
    Abstract: In a non-volatile memory, a selected page on a word line is successively programmed by a series of voltage pulses of a staircase waveform with verifications in between the pulses until the page is verified to a designated pattern. The programming voltage at the time the page is programmed verified will be to estimate the initial value of a starting programming voltage for the page. The estimation is further refined by using the estimate from a first pass in a second pass. Also, when the test is over multiple blocks, sampling of word lines based on similar geometrical locations of the blocks can yield a starting programming voltage optimized for faster programming pages.
    Type: Application
    Filed: September 12, 2006
    Publication date: March 13, 2008
    Inventors: Loc Tu, Charles Moana Hook, Yan Li
  • Publication number: 20080062770
    Abstract: In a non-volatile memory, a selected page on a word line is successively programmed by a series of voltage pulses of a staircase waveform with verifications in between the pulses until the page is verified to a designated pattern. The programming voltage at the time the page is programmed verified will be to estimate the initial value of a starting programming voltage for the page. The estimation is further refined by using the estimate from a first pass in a second pass. Also, when the test is over multiple blocks, sampling of word lines based on similar geometrical locations of the blocks can yield a starting programming voltage optimized for faster programming pages.
    Type: Application
    Filed: September 12, 2006
    Publication date: March 13, 2008
    Inventors: Loc Tu, Charles Moana Hook, Yan Li
  • Patent number: 7254071
    Abstract: A flash memory device of the multi-level cell (MLC) type, in which control gate voltages in read and programming operations and a bandgap reference voltage source are trimmable from external terminals, is disclosed. In a special test mode, control gate voltages can be applied to a selected programmed memory cell so that the threshold voltage of the cell can be sensed. A digital-to-analog converter (DAC) use for programming and a second read/verify DAC apply varying analog voltages and are sequentially used to verify the programming of an associated set of memory cells in this special test mode, with the DAC input values that provide the closest result selected for use in normal operation. These DAC's are dependent on the value of a reference source that my also be trimmed.
    Type: Grant
    Filed: January 12, 2006
    Date of Patent: August 7, 2007
    Assignee: SanDisk Corporation
    Inventors: Loc Tu, Jeffrey Lutze, Jun Wan, Jian Chen
  • Publication number: 20070159888
    Abstract: A flash memory device of the multi-level cell (MLC) type, in which control gate voltages in read and programming operations and a bandgap reference voltage source are trimmable from external terminals, is disclosed. In a special test mode, control gate voltages can be applied to a selected programmed memory cell so that the threshold voltage of the cell can be sensed. A digital-to-analog converter (DAC) use for programming and a second read/verify DAC apply varying analog voltages and are sequentially used to verify the programming of an associated set of memory cells in this special test mode, with the DAC input values that provide the closest result selected for use in normal operation. These DAC's are dependent on the value of a reference source that my also be trimmed.
    Type: Application
    Filed: January 12, 2006
    Publication date: July 12, 2007
    Inventors: Loc Tu, Jeffrey Lutze, Jun Wan, Jian Chen
  • Publication number: 20070159891
    Abstract: A flash memory device of the multi-level cell (MLC) type, in which control gate voltages in read and programming operations and a bandgap reference voltage source are trimmable from external terminals, is disclosed. In a special test mode, control gate voltages can be applied to a selected programmed memory cell so that the threshold voltage of the cell can be sensed. A digital-to-analog converter (DAC) use for programming and a second read/verify DAC apply varying analog voltages and are sequentially used to verify the programming of an associated set of memory cells in this special test mode, with the DAC input values that provide the closest result selected for use in normal operation. These DAC's are dependent on the value of a reference source that my also be trimmed.
    Type: Application
    Filed: January 12, 2006
    Publication date: July 12, 2007
    Inventors: Loc Tu, Jeffrey Lutze, Jun Wan, Jian Chen
  • Publication number: 20070141731
    Abstract: Future operability predictor testing is incorporated into the fabrication of integrated circuits that utilize redundancy. Select reliability testing can be used to identify circuit elements such as memory cells that fail or become defective over time. Future operability tests and associated stress conditions are then developed for application during the fabrication process to identify memory cells that may pose a future operability concern before they actually fail. Memory cells that are determined to pose a future operability concern are replaced by redundant memory cells.
    Type: Application
    Filed: December 20, 2005
    Publication date: June 21, 2007
    Inventors: Gerrit Hemink, Loc Tu, Jian Chen, Kiran Ponnuru
  • Patent number: 7099194
    Abstract: An error recovery technique is used on marginal nonvolatile memory cells. A marginal memory cell is unreadable because it has a voltage threshold (VT) of less than zero volts. By biasing adjacent memory cells, this will shift the voltage threshold of the marginal memory cells, so that it is a positive value. Then the VT of the marginal memory cell can be determined. The technique is applicable to both binary and multistate memory cells.
    Type: Grant
    Filed: December 3, 2004
    Date of Patent: August 29, 2006
    Assignee: SanDisk Corporation
    Inventors: Loc Tu, Jian Chen
  • Publication number: 20050094440
    Abstract: An error recovery technique is used on marginal nonvolatile memory cells. A marginal memory cell is unreadable because it has a voltage threshold (VT) of less than zero volts. By biasing adjacent memory cells, this will shift the voltage threshold of the marginal memory cells, so that it is a positive value. Then the VT of the marginal memory cell can be determined. The technique is applicable to both binary and multistate memory cells.
    Type: Application
    Filed: December 3, 2004
    Publication date: May 5, 2005
    Applicant: SanDisk Corporation
    Inventors: Loc Tu, Jian Chen
  • Patent number: 6829167
    Abstract: An error recovery technique is used on marginal nonvolatile memory cells. A marginal memory cell is unreadable because it has a voltage threshold (VT) of less than zero volts. By biasing adjacent memory cells, this will shift the voltage threshold of the marginal memory cells, so that it is a positive value. Then the VT of the marginal memory cell can be determined. The technique is applicable to both binary and multistate memory cells.
    Type: Grant
    Filed: December 12, 2002
    Date of Patent: December 7, 2004
    Assignee: SanDisk Corporation
    Inventors: Loc Tu, Jian Chen